The present invention relates, in general, to vapor generators, and, in particular, to a new and useful boiler system with a furnace which is adapted for burning, in addition to conventional fuel, municipal solid waste or kraft black liquor of the paper industry.
Such boiler systems may include a superheater and an economizer in a convection pass downstream of a combustion chamber. An additional boiler assembly may also be provided between the superheater and the economizer. It is known to provide a plurality of steam and water drums, which, in particular, are connected to steam generating tubes for receiving a steam/water mixture and separating the mixture into a steam supply and a water supply.
Particular problems occur when dealing with boiler systems for burning kraft liquors and solid waste, in that, inordinate amounts of soot and other impurities are generated which tend to foul heat transfer tubing of the superheaters, boilers and economizers.
Particularly in view of rising energy costs, it has become increasingly interesting to utilize such wastes to generate steam. This interest has resulted in the demand for higher steam pressures and temperatures with extended superheater control ranges.
In addition to the fouling problems in burning kraft liquors, water can leak into the smelt bed formed at the bottom of the furnace chamber which can cause severe explosion and fire problems due to smelt-water reactions. Close quality control is thus required in the manufacture and construction of pressure parts for such boiler systems.
Another problem arises, in particular, with the burning of municipal solid wastes, in that excess soot and ash material must be dislodged from tubes of heat transfer surface.